Alternator question

MissouriJim · Post by **MissouriJim** » 05 Feb 2023, 15:27

Hi Folks,

The symptom is no charge from the alternator.

- Charge dash light does NOT illuminate with the others when I key-on before starting - does not come on at all.
- Charge dash light WILL illuminate if I manually ground the exciter wire (small red/white wire normally attached to the alt.)

Does this mean the alternator is somehow internally fried? I understand enough to know the exciter is supposed to somehow kick-start the alternator, but nothing more than that.

TIA,
-Jim

Post by **scot850** » 05 Feb 2023, 15:51

Has your car been jump started recently? That can sometimes damage the alternator if the wires were reversed.

The dash warning light should come on at position II with the ignition key. If it does not then the bulb may be out or the alternator is bad. Normally the alternators are good if the bearings are not rumbling. It is the internal voltage regulator that wears out/fails.

Neil.

Post by **Chuck W** » 05 Feb 2023, 15:53

Sounds like the bulb is good, but the alternator/regulator is bad.

WhatAmIDoing · Post by **WhatAmIDoing** » 05 Feb 2023, 17:22

Usually the voltage regulator fails. As long as the bearings are still good, Can be replaced without removing the alternator if you have enough patience. You will have to remove the regulator anyway to test the alternator windings /stator for shorts.

Post by **BEJinFbk** » 05 Feb 2023, 21:45

Start the car.

Measure the voltage between ground
and the big post on the alternator.

What does it read?

Post by **MrAl** » 06 Feb 2023, 06:20

Hey i'll check mine too. Maybe i have a semi bad wire (higher resistance than normal).

I had several alternators go on my old Hyundai. After replacing the ground connection has to be tight.
I really think they should use four wire power and sense. Maybe they are afraid if the sense wires get broken the alternator will fry the battery, but with all the other gadgets i would think they could have a fail safe and indicator light for that.
If i had my way i would install such a setup, but i cant seem to get to my alternator. It's really buried (see pics).

Dont know what all the terminals are for either.

MissouriJim · Post by **MissouriJim** » 06 Feb 2023, 08:27

Great advice, all.

Since my power steering pump makes a lot of noise, I'll change it at the same time. So that makes removing the alt. clearly the best approach.

I'll remove the pump and alt. in the next cpl days, then I'll take a look at the regulator and see if there's clear damage I can repair or not. Then, I'll visit the yard for the appropriate bits this weekend.

-Jim

WhatAmIDoing · Post by **WhatAmIDoing** » 06 Feb 2023, 11:10

MissouriJim wrote: ↑06 Feb 2023, 08:27 Great advice, all.

Since my power steering pump makes a lot of noise, I'll change it at the same time. So that makes removing the alt. clearly the best approach.

I'll remove the pump and alt. in the next cpl days, then I'll take a look at the regulator and see if there's clear damage I can repair or not. Then, I'll visit the yard for the appropriate bits this weekend.

-Jim

I would just order a new voltage regulator, ~$40. Reduced the risk of having to do it again.

Post by **BEJinFbk** » 06 Feb 2023, 12:21

Have you confirmed the problem?

Step 1 - Check the power supply.
Step 2 - Refer to Step 1.

What is the voltage at the alternator
when the car is running?

MissouriJim · Post by **MissouriJim** » 06 Feb 2023, 13:26

WhatAmIDoing wrote: ↑06 Feb 2023, 11:10 I would just order a new voltage regulator, ~$40. Reduced the risk of having to do it again.

Can you advise where I can source this? The only inexpensive ones were Chinese-made on Ebay from relatively unknown sellers.

IPDUSA has them for around $200